My virtual machine can't ping itself

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Hello,

I'm using Ubuntu indigo 14.04 with Oracle VirtualBox 5.2.18 and I have a problem with my Virtual machine which can't ping itself but can ping all the network. Also, the other computers can ping each other but can't ping the virtual machine. My network is composed by : 2 virtual machines (chloe and another one) on the main station, the main station, a first router, the second router in client mode, an Advantech computer on a robot and Ubuntu on this computer (efim).

So, from chloe, I can ping all of this stuff but not chloe itself. I had the issue : "Destination Host Unreachable" while I'm just pinging chloe itself.

In the settings, I choose NAT for the Virtual Machine.

Moreover, I tried a

roswtf

and I have the following warning :

  ROS_HOSTNAME may be incorrect: ROS_HOSTNAME [chloe] resolves to [192.168.0.6], which does not appear to be a local IP address ['127.0.0.1', '10.0.2.15', '192.168.1.2', '169.254.7.89'].

What I did after this is : for main station

    export ROS_HOSTNAME=chloe
    export ROS_MASTER_URI=http://chloe:11311

for advantech

    export ROS_HOSTNAME=efim
    export ROS_MASTER_URI=http://chloe:11311

But after I have an error saying :

  ROS_MASTER_URI is not set for this machine

Anyone can help me please ?

Thanks.